OFFSET
1,2
COMMENTS
It is conjectured that the subsequence of noncube terms, A045911, is finite (has 6195 terms). But there are infinitely many cubes in this sequence: k^3 if a term if and only if k^3 - (k-1)^3 = 3*k^2 - 3*k + 1 is a nonprime (k-1 is in A257772). For example, for k == 2, 6 (mod 7), 3*k^2 - 3*k + 1 is divisible by 7, so k^3 is a term for k == 2, 6 (mod 7) and k > 2.
EXAMPLE
9 is a term since neither 9 - 0^3 = 9 nor 9 - 1^3 = 8 is a prime.
PROG
(PARI) isA356295(n) = for(m=0, sqrtnint(n, 3), if(isprime(n-m^3), return(0))); return(1)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jianing Song, Aug 03 2022
STATUS
approved